A cement composition, such as mortar or concrete, generally contains cement, an aggregate, and water, and preferably further contains a cement additive that functions as a water-reducing agent or a cement additive that functions as a retaining agent for improving its fluidity to reduce its water content (for example, Patent Literature 1).
It can be said that the cement additive that functions as a retaining agent is an additive that can express more excellent retention as a change in fluidity of the cement composition with time becomes smaller.
In addition, when a specific polycarboxylic acid-based copolymer is used as a polymer component of any such cement additive, at the time of the production of the copolymer, in general, a persulfate is used as an initiator and NaOH is used in the neutralization of the persulfate after the polymerization of the copolymer. However, when NaOH used in the neutralization after the polymerization, Glauber's salt (Na2SO4) is produced as a by-product, and under low temperature, the Glauber's salt crystallizes to cause a trouble, such as the clogging of various apparatus. Meanwhile, when the neutralization is not performed after the polymerization so that the production of the Glauber's salt as a by-product may be suppressed, a problem in that the acidity of the cement additive strengthens and hence various apparatus are corroded occurs.